[jQuery] Ajax ,dataType and success

[raoh]

this is my code, a normal code as the examples on jquery.com
ajax.php can only echo "OK1", "OK2" or "KO", so I wonder why none of
the if in the success function work ? but the alert before works well
and i set dataType = text just to be sure. It's like mess is another
type of variable or what ? Thank you

$.ajax({
        type:"POST",
        url:"ajax.php",
        data:"act=buy,
        cache:false,
        dataType: "text",
        beforeSend: function(){
            // Loading
        },
        success: function(mess){
            var txt = mess;
                        alert(txt);
            if(txt=="OK1")
                alert(txt);
            if(txt=="OK2")
                alert(txt);
            if(txt=="KO")
                alert(txt);

        },
        error: function(){
            // Errore
        }
    });